1. Field of the Invention
The present invention relates to a light emitting device having a plurality of light emitting elements and a method of manufacturing the same.
2. Description of the Related Art
In recent years, in the field of a semiconductor laser, a multiwavelength laser having a plurality of light emitting sections of different light emission wavelengths on the same substrate (or a base) is actively developed. The multiwavelength laser is used, for example, as a light source of an optical disk device.
In such an optical disk device, a laser beam in the 700 nm band is used for reproducing a CD (Compact Disk) and used for recording/reproducing a recordable optical disk such as a CD-R (CD Recordable), a CD-RW (CD Rewritable) or an MD (Mini Disk). A laser beam in the 600 nm band is used for recording/reproducing a DVD (Digital Versatile Disk). By mounting a multiwavelength laser on an optical disk device, any of existing optical disks of a plurality of kinds is recorded or reproduced. Further, a laser having a short wavelength (400 nm band) using a nitride-based III-V group compound semiconductor typified by GaN, AlGaN, and GaInN (hereinbelow, called a GaN-based compound semiconductor) is realized and is practically used as a light source of an optical disk of higher density. By using multiwavelength also for a short-wavelength laser, the applications are further expanded.
A 3-wavelength laser device (light emitting device) having such a GaN-based laser oscillator, which is manufactured, for example, by the following method is conventionally proposed. Specifically, first, a GaN-based compound semiconductor is grown on a GaN substrate to form a first light emitting element having a wavelength in the 400 nm band. On the same GaAs substrate, a second light emitting element is formed by providing an element in the 600 nm band by growing an AlGaInP-based compound semiconductor and an element in the 700 nm band by growing an AlGaAs-based compound semiconductor in parallel. The first and second light emitting elements are disposed so as to overlap in this order on a supporting base. In such a manner, conventionally, a 3-wavelength laser device is fabricated. In the conventional 3-wavelength laser device, heat generated in the second light emitting element is dissipated from the GaN substrate and the supporting base having excellent thermal conductivity, so that high heat dissipation efficiency is obtained.
Such a light emitting device is formed by, for example, mounting a first light emitting element on a supporting base, forming a plurality of gold bumps on the supporting base, and mounting a second light emitting element on the gold bumps and the first light emitting element (refer to Japanese Unexamined Patent Application Publication No. 2007-234643). The gold bump has a function of a heat sink for dissipating heat generated in the second light emitting element and a function of supplying power from the supporting base side to the second light emitting element.